At the ripe age of 28, Jon Zimmer is sort of an old fogey. That is, he is obsessive about the sound quality of his music. A onetime audio engineer who now works as a consultant for Stereo Exchange, an upscale audio store in Manhattan, Mr. Zimmer lights up when talking about high fidelity, bit rates and $10,000 loudspeakers.

But iPods and compressed computer files — the most popular vehicles for audio today — are “sucking the life out of music,” he says.

The last decade has brought an explosion in dazzling technological advances — including enhancements in surround sound, high definition television and 3-D — that have transformed the fan’s experience. There are improvements in the quality of media everywhere — except in music.

In many ways, the quality of what people hear — how well the playback reflects the original sound— has taken a step back. To many expert ears, compressed music files produce a crackly, tinnier and thinner sound than music on CDs and certainly on vinyl. And to compete with other songs, tracks are engineered to be much louder as well.

In one way, the music business has been the victim of its own technological success: the ease of loading songs onto a computer or an iPod has meant that a generation of fans has happily traded fidelity for portability and convenience. This is the obstacle the industry faces in any effort to create higher-quality — and more expensive — ways of listening.

“If people are interested in getting a better sound, there are many ways to do it,” Mr. Zimmer said. “But many people don’t even know that they might be interested.”

Take Thomas Pinales, a 22-year-old from Spanish Harlem and a fan of some of today’s most popular artists, including Lady Gaga, Jay-Z and Lil Wayne. Mr. Pinales listens to his music stored on his Apple iPod through a pair of earbuds, and while he wouldn’t mind upgrading, he is not convinced that it would be worth the cost.

The change in sound quality is as much cultural as technological. For decades, starting around the 1950s, high-end stereos were a status symbol. A high-quality system was something to show off, much like a new flat-screen TV today.

But Michael Fremer, a professed audiophile who runs musicangle.com, which reviews albums, said that today, “a stereo has become an object of scorn.”

The marketplace reflects that change. From 2000 to 2009, Americans reduced their overall spending on home stereo components by more than a third, to roughly $960 million, according to the Consumer Electronics Association, a trade group. Spending on portable digital devices during that same period increased more than fiftyfold, to $5.4 billion.

“People used to sit and listen to music,” Mr. Fremer said, but the increased portability has altered the way people experience recorded music. “It was an activity. It is no longer consumed as an event that you pay attention to.”

Instead, music is often carried from place to place, played in the background while the consumer does something else — exercising, commuting or cooking dinner.

The songs themselves are usually saved on the digital devices in a compressed format, often as an AAC or MP3 file. That compression shrinks the size of the file, eliminating some of the sounds and range contained on a CD while allowing more songs to be saved on the device and reducing download times.

Even if music companies and retailers like the iTunes Store, which opened in April 2003, wanted to put an emphasis on sound quality, they faced technical limitations at the start, not to mention economic ones.

“It would have been very difficult for the iTunes Store to launch with high-quality files if it took an hour to download a single song,” said David Dorn, a senior vice president at Rhino Entertainment, a division of Warner Music that specializes in high-quality recordings.

The music industry has not failed to try. About 10 years ago, two new high-quality formats — DVD Audio and SACD, for Super Audio CD — entered the marketplace, promising sound superior even to that of a CD. But neither format gained traction. In 2003, 1.7 million DVD Audio and SACD titles were shipped, according to the Recording Industry Association of America. But by 2009, only 200,000 SACD and DVD Audio titles were shipped.

Last year, the iTunes Store upgraded the standard quality for a song to 256 kilobits per second from 128 kilobits per second, preserving more details and eliminating the worst crackles.

Some online music services are now marketing an even higher-quality sound as a selling point. Mog, a new streaming music service, announced in March an application for smartphones that would allow the service’s subscribers to save songs onto their phone. The music will be available on the phone as long as the subscriber pays the $10 monthly fee. Songs can be downloaded at up to 320 kilobytes per second.

Another company, HDtracks.com, started selling downloads last year that contain even more information than CDs at $2.49 a song. Right now, most of the available tracks are of classical or jazz music.

David Chesky, a founder of HDtracks and composer of jazz and classical music, said the site tried to put music on a pedestal.

“Musicians work their whole life trying to capture a tone, and we’re trying to take advantage of it,” Mr. Chesky said. “If you want to listen to a $3 million Stradivarius violin, you need to hear it in a hall that allows the instrument to sound like $3 million.”

Still, these remain niche interests so far, and they are complicated by changes in the recording process. With the rise of digital music, fans listen to fewer albums straight through. Instead, they move from one artist’s song to another’s. Pop artists and their labels, meanwhile, shudder at the prospect of having their song seem quieter than the previous song on a fan’s playlist.

So audio engineers, acting as foot soldiers in a so-called volume war, are often enlisted to increase the overall volume of a recording.

Randy Merrill, an engineer at MasterDisk, a New York City company that creates master recordings, said that to achieve an overall louder sound, engineers raise the softer volumes toward peak levels. On a quality stereo system, Mr. Merrill said, the reduced volume range can leave a track sounding distorted. “Modern recording has gone overboard on the volume,” he said.

In fact, among younger listeners, the lower-quality sound might actually be preferred. Jonathan Berger, a professor of music at Stanford, said he had conducted an informal study among his students and found that, over the roughly seven years of the study, an increasing number of them preferred the sound of files with less data over the high-fidelity recordings.

“I think our human ears are fickle. What’s considered good or bad sound changes over time,” Mr. Berger said. “Abnormality can become a feature.”